The variability of outer code failure rate of memory pages of a solid state memory device can be reduced by selectively grouping the pages included in the outer code words. The data in the page groups are encoded into outer code words which are stored in the memory device. Encoding the data of the page groups and storing the encoded data includes intermittently accumulating an outer code parity as the pages are sequentially stored in the memory device according to a particular order. The pages can be randomly selected for the page groups or can be grouped based on predicted or measured failure rate information. In a memory device having multi-level memory cells, predicting the failure rate of a page can be based on whether the page is a most significant bit (MSB) page or a least significant bit (LSB) page.